In a dynamo-electric machine, a rotating magnetic field is generated by supplying AC power to a stator winding wire and a rotator is rotated by the rotating magnetic field. Further, it is also possible to convert mechanical energy added to a rotator into electric energy and output AC power from a coil. In this way, a dynamo-electric machine operates as an electric motor or an electric generator.
As a stator of such a dynamo-electric machine, a configuration of connecting terminals of segment coils by welding is known (refer to Japanese Patent Laid-Open No. 2011-151975, for example).
When a dynamo-electric machine of this kind is mounted over an automobile, downsizing is required because the dynamo-electric machine is attached in a narrowly limited space. Low coil ends have been required in association with the downsizing. To this end, it is required to reduce the height of a coil end part and secure an insulation distance in a narrowly limited space. To secure a stable insulation distance in a segment coil has been a problem. Further, after switching operation of a switching element in an inverter apparatus, a steep surge voltage is inputted from the inverter apparatus to the input point of each phase. On this occasion, although it is desirable to optimize the thickness of an insulation film in proportion to the voltage sharing ratio of each coil, the thickness of the insulation film of each coil can be difficult to be increased because the increase of thickness causes productivity to deteriorate from the viewpoint of the formability of the coil.